Flying Formations

There has been a question on my mind for a while now…. What factors affect the flying formation of birds? 

As it is now autumn and getting colder there are many birds starting to fly to warmer climates (either in the UK or abroad), and I have therefore seen lots of birds past whilst walking Pippin. 

In the typical 'V' shaped formation, what affects the order?

• Hierarchy (the pecking order)
• Fastest flying birds at front
• Random formation
• Relationships within the group
• Confidence of navigation

Why do bird fly in the 'V' shaped formation?

• Aerodynamic 
• Easier to navigate? - less likely to veer off in the wrong direction
• slip-stream (like with cyclists) - why don't they fly in the straight line then?
• Easily shows hierarchy
• All the birds can see the leader - presuming its in order of hierarchy 

Why are some formations not 'V' shaped?

• Number of birds in the group
• Species of birds
• Experience of birds 
• Not as effective with too many birds
• some species may have better aerodynamics and therefore don't need to be in a formation

Why does the formation constantly change?

• gusts of wind could move them about
• slip-stream (cyclists) - tired birds move to the back as the bird at the front do more work
• birds need to communicate with the leader?
• competitive within the group, some sort of race

Why are there sometimes sub-groups or individuals flying alongside the main group?

• Different families
• Different ages/species/social classes?
• outcast birds could fly solo alongside the group
• more anti-socials birds fly solo
• could be a completely different group of birds

A large group of 25 birds in a typical V formation

 The group of 25 is then joined by 2 sub-groups, each 6 birds strong.

The front 8 birds on the left hand side (not including the leader) then peel of and form a soldiery diagonal line.

Here is another group of birds, 9 strong in a V formation. From the birds perspective there are 3 birds on the right and 5 on the left, and the leader up front.

As the birds passed over head, it became very clear that the V was unevenly distributed. The formation could have been even (4 on each side, leader at front,) but the birds instead flew like this. Why did the birds choose to fly like this? Could 2 birds of split up from the group, leaving it uneven? 

As the birds flew into the distance, the bird at the front speeds up and separated itself from the group. Why?

These are all questions I want to look into and maybe even figure out myself.